Threat Assessment Levels


Thunderstorms:

Blue: A few thunderstorms are possible. Little or no severe threat.
Green: Widely scattered to scattered thunderstorms are expected. Little severe threat.
Yellow: Scattered to numerous thunderstorms are expected. A few storms could be severe or could produce heavy rainfall (see severe and rainfall TAMs for details).
Orange: Scattered to numerous thunderstorms with severe weather or heavy rainfall is expected. (see severe and rainfall TAMs for details).
Red: Widespread severe thunderstorms are likely. A significant outbreak is expected (see severe weather and rainfall TAMs for details).

Tornadoes:

Blue/Green: A tornado or two could occur in these areas. A widespread outbreak is not expected.
Yellow: Conditions are generally favorable for tornadoes, however the threat is localized, conditional and/or not expected to generate a widespread outbreak. A strong tornado (EF2+) could occur where conditions are the most favorable.
Orange: Conditions are very favorable for tornadoes and a few strong/violent tornadoes can be expected in the threat area.
Red: A widespread outbreak, including multiple long track, violent tornadoes are expected.

Damaging Wind/Hail:

Blue: Isolated strong wind gusts or small hail is possible. Little severe threat is expected.
Green: A few reports of severe wind gusts >58mph or hail >1″ are possible.
Yellow: Several reports of severe wind gusts >58mph or hail >1″ are likely. A report or two of significant wind gusts >75mph or hail >2″ is possible.
Orange: A significant severe wind and/or hail event is possible. Widespread reports of severe wind gusts >58mph or hail >1″ are likely. Several reports of wind gusts >75mph and/or hail >2″ are likely. When used for a wind event, widespread power outages are possible.
Red: An exceptional severe wind and/or hail event is expected. Numerous reports of significant severe weather (>75mph winds and >2″ hail) are expected and widespread reports of wind gusts >58mph or hail >1″. When used for a wind event, widespread power outages are likely.

Snow:

Blue:  Minor snowfall under an inch and/or little to no traffic impact or impact on everyday life.
Green: Light snowfall from 1 to 3″ and/or minor to moderate traffic impact and minor impact on everyday life.
Yellow: Moderate snowfall from 3″ to “6 and/or moderate to high traffic impact and moderate impact on everyday life.
Orange: Major snowfall from 6″ to 9″ and/or high traffic impact, school closings possible, and moderate impact on everyday life.
Red: Significant snowfall greater than 9″ and/or high traffic impact, school closings likely, high impact on everyday life.

Ice:

Blue:  Glaze of ice . Little traffic impact or impact on everyday life.
Green: Light accrual up to 0.10″. Minor to moderate traffic impact and minor impact on everyday life.
Yellow: Moderate accrual up to 0.25″. Moderate to high traffic impact and moderate impact on everyday life.
Orange: Major accrual up to 0.50″. High traffic impact, school closings possible, and moderate impact on everyday life.
Red: Significant accrual over 0.50.” High traffic impact, school closings likely, high impact on everyday life.

Flooding:

Green: Minor river, stream or areal flooding. Vulnerable, low-lying areas are most affected. Localized flash flooding during thunderstorm events. Travel disruption is limited.
Yellow:  Moderate river, stream or areal flooding. Significant flash flooding during thunderstorm events. Some disruption to travel is possible.
Red: Major river, stream or areal flooding. Widespread and significant flash flooding due to successive thunderstorm events on saturated soil. Scattered to widespread travel disruption is possible. Structure damage due to excessive flooding is possible. Evacuations are possible as well.

Excessive Heat:

Yellow: Air temperatures >95F or heat indexes >100F, or air temperatures >90F  or heat indexes >95F for at least five consecutive days.
Orange: Heat wave. Air temperatures >100F or heat indexes >105F, or air temperatures >95F or heat indexes >100F for at least three consecutive days. Significant heat stress possible.
Red: Dangerous heat wave. Air temperatures >105F or heat indexes >110F for one day, or air temperatures >100F or heat indexes >105F for three consecutive days. Widespread health risk due to heat stress. Avoid prolonged outdoor activities.

Extreme Cold:

Blue: Air temperatures <0F or Wind chills <-10F, or air temperatures <5F  or wind chills <0F for at least five consecutive days.
Green: Bitter cold. Air temperatures <-5F or wind chills <-20F, or air temperatures <0F or wind chills <-10F for at least three consecutive days. Significant frost bite possible.
Yellow: Dangerous cold. Air temperatures <-10F or wind chills <-30F for one day, or air temperatures <-5F or wind chills <-20F for three consecutive days. Widespread health risk due to frost bite or hypothermia. Avoid prolonged outdoor activities.